The present invention relates generally to an internal combustion engine having an improved liquid cooling circuit which substantially improves the operating conditions of the engine, consequently reducing in a very significant manner the proportions of noxious products in the exhaust gases.
In order to increase the thermal efficiency and reduce the polluting nature of internal combustion engines, research has been directed both towards improving the internal operation of the engine and to treating the exhaust gases, mainly by thermal or catalytic after-burning. In order to obtain a sufficiently low level of noxious products, it is often necessary to call on both types of improvement within the same engine.
The present invention improves the circulation of cooling liquid within the engine. In order to optimize thermal efficiency, it is important to maintain an uniform operating temperature at all portions of the engine. In presently known engines, and more particularly in engines with cylinders arranged in line, the cooling liquid circulates parallel to the axis of the crankshaft and to the alignment of the cylinders, in the space located between the cylinders and the cylinder block as illustrated generally in FIGS. 1 and 2 of the drawings. Whatever may be the improvements which are effected (acceleration, increased pressure, composition of the cooling liquid, etc.), there always exists a temperature gradient between the input and the output of the cooling liquid. Thus the temperature in the combustion chamber of the first cylinder is different from that of the last cylinder. Furthermore, because the flow cross-section of the cooling liquid varies, turbulence is necessarily created between the cylinder block and the cylinders which generates hot spots, thereby spoiling optimum operation of the engine.